Motion capture devices are used to detect the motion of objects and use the captured motion as an input to a computer system. Motion capture devices are typically small devices connected to computers and located between a user and a display. Some motion capture devices are located on a surface between a user and the display and detect motion in a 3-dimensional sensing region located above the motion capture device. Motion capture devices may use a combination of cameras, light detectors, and light emitters to detect objects in the sensing region. For example, a motion capture device may include two cameras located a set distance apart and an array of illuminators. The illuminators illuminate an object above the motion capture device and a series of images from each camera are used to determine the location, shape and movement of the object.
Motion capture devices are commonly used to detect gestures in the 3-dimensional sensing area above the motion capture device. For example, a gesture may include a series of specific movements of a user's hand or a stylus that has a specific command in an application associated with it. Motion capture devices are also used to detect motion to control a virtual object such as a cursor. Merely following motion of a user's hand, for example, limits the motion capture system to inputs discernible from the hand and its motions. Rather, it would be advantageous to add tool to hand, such as a stylus for example, and tool detection capabilities to the motion capture device. Accordingly, the device could detect a user pointing to different portions of a display by detecting the movement of a stylus held by the user and move the cursor to the appropriate portion of the display. Unfortunately, however, this scenario fails today because the stylus in this example has such limited functionality, e.g., functionality of the system is limited to the detection of the stylus and its motion. In such a system the motion capture device system does not differentiate two identical movements of a stylus.